Turbocharged and supercharged engines may be configured to compress ambient air entering the engine in order to increase power. Compression of the air may cause an increase in air temperature, thus, an intercooler or charge air cooler (CAC) may be utilized to cool the heated air thereby increasing its density and further increasing the potential power of the engine. Condensate may form in the CAC when the ambient air temperature decreases, or during humid or rainy weather conditions, where the intake air is cooled below the water dew point. Condensate may collect at the bottom of the CAC, or in the internal passages, and cooling turbulators. When torque is increased, such as during acceleration, increased mass air flow may strip the condensate from the CAC, drawing it into the engine and increasing the likelihood of engine misfire and combustion instability.
One approach to address condensate formation in the CAC may involve draining condensate from the CAC to the intake manifold of the engine. However, this method may not allow for adequate vaporization of the condensate before entering the engine. Thus, liquid condensate entering the engine may cause combustion instability and misfire.
In one example, the issues described above may be addressed by a method for draining condensate from a charge air cooler and introducing the condensate to at least one of a positive crankcase ventilation flow or an engine oil sump. Specifically, the condensate may be drained into a liquid storage reservoir, positioned adjacent to an engine block or exhaust manifold to allow evaporation of the liquid condensate. Water vapor may then enter the crankcase ventilation flow into the engine and/or liquid condensate may enter the engine oil sump for evaporation and disposal. In this way, the condensate may be evaporated and disposed of in a way that reduces the potential for engine misfire.
In one example, condensate may automatically drain from the charge air cooler into the liquid storage reservoir. A drain valve or orifice may be used to control flow of liquid condensate into the engine oil sump. For example, a controller may adjust the drain valve in response to conditions of the liquid storage reservoir and the engine oil sump. The conditions of the liquid storage reservoir and the engine oil sump may include a liquid condensate level in the liquid storage reservoir, an oil temperature in the engine oil sump, a pressure difference between the liquid storage reservoir and the engine oil sump, and a fluid level in the engine oil sump. For example, the drain valve may open when the liquid condensate level in the liquid storage level is greater than a threshold level, the oil temperature is greater than a threshold temperature, the pressure difference between the liquid storage reservoir and the engine oil sump is less than a threshold difference, and the fluid level in the engine oil sump is less than a threshold fluid level. In this way, the drain valve may be adjusted to allow disposal of liquid condensate into an engine oil sump where it may evaporate.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.